Generally, in a strainer of ECCS recirculation sump in an emergency core cooling system of a nuclear power plant, there is a problem that cooling water circulation is not facilitated due to head loss, as emergency operation time is increased. Therefore, it is necessary to estimate whether the strainer can be used during the recirculation mode. In the prior art, the ALDEN company, CCI company, ALION company, VUEZ company and the like built an individual head loss test apparatus and a hydraulic test apparatus and measured the performance of the strainer.
The individual head loss test apparatus is to perform a small-scale test for the strainer, i.e., to test the filtering performance of a test piece of the strainer in restricted surroundings.
The hydraulic performance test apparatus is to simulate the hydraulic characteristics around the strainer, and this test is also performed in restricted surroundings.
However, since it is not possible to estimate various on-the-spot factors which have an influence on the strainer performance, except some factors, there is a problem that the reliability of estimation is lowered.
The on-the-spot factors are various, such as a kind and component ratio of debris, a flow rate, temperature and pressure of water, a flow passage around the strainer and the like. The conventional apparatuses can estimate only some of the factors, and particularly a debris interceptor which is disposed at a flow passage directed to the sump; having the strainer directly reduces the debris, such that the head loss of the strainer is reduced. The debris interceptor is also one of the factors which has an influence to the head loss of the strainer, and thus it is necessary to consider a complicated correlation between the debris interceptor and other factors. However, the complicated correlation has not been estimated in the prior art.